There are costs and benefits associated with living in groups. A. Solitary animals are sometimes thought to be higher up the evolutionary scale because they leave more surviving descendants on average than social animals do. B. Social animals have evolved fewer mechanisms for reducing the costs of competing for social status than they have for reducing the risks of exposure to disease and parasites. C. The need for protection from predators makes animals adopt social living, but animals that have the ability to individually fight off predators benefit more from solitary living. D. Social living has advantages such as making it possible for animals to become more successful at locating food, but it also has risks such as increased competition for mates. E. The numerous disadvantages of living together lead animals to adopt social living only when the benefits are greater than the costs. F. Animals that live alone such as pumpkinseed fish need to evolve a special mouth or some other special organ to help them combat predators.